I dont lame up seige spots, i put 1-2 OCS in there against a area where a Marine can only see it / shoot it if he enters the room forcing himself to be shot multiple times. Usually Ninjas run by them easily, so for instance:
Maint. Hive in eclipse. The famous seige spot:
1: This is the uncecessary "prevention" spot. Only do this if you have more then enough res. Its can easily be sniped out by marines, but can do alot of damage if the marines are caught off guard. It also is a First Line of defense, because marines have to take them down before building, so you know where they are.
2: The siege spot, this is the dangerous zone for aliens if marines get a phase gate up. I put 2 OCS down the ramp on the angle slightly. Marines can ONLY see this if they ENTER the seige area. Thus no sniping or anything, (especially if the #1's are still there.
and 3: This is for your prevention of Ninjas. (The DC was there so i built an OC on top so the marine couldnt take cover behind it.)
Basically i put the OCS on the rail / on the angles so they can shoot easier, and since FF is on in LM there shots are never blocked by one another. NO marine will be getting by this unless hes medspammed. But by then im sure he wont be unnoticed.
Total res Spent on OCS: 70 (thats alot of res)
Total res spent in areas NECESSARY: 30 (2 on ramp, one next to the OC on top of the DC)
That ends my Maint tutorial / guideline / suggestion post. As for DCS, i put em in vent or on top of hives.
I usually gorge to put up OC spots or Res towers. i dont bother with the dcs/mcs/sc/s let someone else do that ^^.
If you need any more "guidelines/ suggestions" on effective seige/ ninja spots just ask and tell me the area. Ill be more then glad to do what i did above again.